Old Reservoir
Randolph County, Missouri21 acresView mapDirections
Missouri DNR publishes the water-quality measurements for Old Reservoir. Here is what has been measured.
- Eutrophic
- Public access
Old Reservoir in Randolph County, Missouri has water-quality measurements published by Missouri DNR, shown here as reported. Water clarity: 3.6 ft visibility. Phosphorus: 33 µg/L. Chlorophyll-a (algae): 14.2 µg/L. Surface area: 21 acres.
Old Reservoir is a 21-acre productive, nutrient-rich eutrophic lake in Randolph County, Missouri. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 6 other monitored lakes in Randolph County, Old Reservoir ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2024-09-17. Methodology: how these readings are compared.
What Old Reservoir is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
Readings onlyModerate algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Old Reservoir is safe to swim in today is a call for the Missouri Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Old Reservoir
These are the measurements Missouri DNR publishes for Old Reservoir, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 3.6 ft. Phosphorus 33 µg/L. Chlorophyll-a 14.2 µg/L. TSI 57.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.6ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 33µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 14.2µg/L | Fair GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 57 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Old Reservoir
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Old Reservoir typically sits around 74°F at the surface in September. Summer average is about 80°F. Usually warmest in Jul (about 82°F) and coldest in Apr (about 59°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (59°F) to its warmest (82°F).
Typical surface water temperature by month, from 98 field readings (2010–2024) via the EPA Water Quality Portal. See the full Old Reservoir water temperature breakdown →
Lake Details
Surface area
21 acres
Public access
Yes
Listed by Missouri DNR
No bathymetric survey has been published for Old Reservoir, so its depth is not documented here.
Recreation & Access
- Water Works Lake (Moberly)Public
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
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Stays near Old Reservoir
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Fishing Old Reservoir
Water Quality Trend: Improving
Based on 5 years of monitoring (2020–2024).
Water clarity
Improving5 years
Phosphorus
Improving-4.33 µg/L/yr5 years
Chlorophyll-a
Improving-3.81 µg/L/yr5 years
Reservoir Info (USACE NID)
Old Reservoir is a man-made reservoir impounded by the Water Works Lake Dam (completed 1870), built primarily for recreation on the TRIBUTARY TO SWEET SPRING CRK; earth-type dam, 30 ft tall.
- Surface area
- 21 ac
- Normal storage
- 147 ac-ft
- Max storage
- 337 ac-ft
- Drainage area
- 418 sq mi
- Hazard class
- High
- Owner
- MOBERLY-PARKS&RECREATION
All listed purposes: Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID MO10006 · Operator website · Matched by proximity (0.04 km)
Regulated Pollution Sources Nearby
4 EPA-permitted facilities operate within about 5 miles of Old Reservoir under Clean Water Act (NPDES) discharge permits. 4 facilities have a reported Clean Water Act violation in the past three years.
- Fox Hollow Wastewater Treatment FacilityMoberly · 1.2 mi away · NPDES MO0035599Recent violation
- Orton Lane WwtfMoberly · 1.7 mi away · NPDES MO0121622Recent violation
- Heritage Hills Golf Course WwtfMoberly · 2 mi away · NPDES MO0095605Recent violation
- Moberly Mo Llc WwtfMoberly · 3.1 mi away · NPDES MO0045021Recent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Nearby Lakes in Randolph County
Frequently asked questions about Old Reservoir
Where is Old Reservoir?
- Old Reservoir is a lake in Randolph County, Missouri. Its water-quality measurements are published by Missouri DNR and shown on this page as reported.
What is the water quality of Old Reservoir?
- Old Reservoir in Randolph County, Missouri has water-quality measurements published by Missouri DNR, shown here as reported. Water clarity: 3.6 ft visibility. Phosphorus: 33 µg/L. Chlorophyll-a (algae): 14.2 µg/L. Surface area: 21 acres.
Is Old Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Old Reservoir?
- Old Reservoir typically sits around 74°F at the surface in September, from 98 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
Are there boat ramps on Old Reservoir?
- Old Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Water Works Lake (Moberly). Public access is listed as yes.
Can I fish at Old Reservoir?
- Old Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Missouri's fish and wildlife agency, so check its current regulations before you go.
Explore Old Reservoir across LakeQuality
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Where this data comes from
120 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Univ. of Missouri, Columbia
UMC120 samples · 2020–2024
Analytical methods
- Depth, Secchi disk in meters
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Named boat-access points from the USGS National Boat Ramps inventory